Cellulose acetate crepe yarns and fabrics, and their manufacture



Patented Aug. 15, 1

UNITED STATES PATENT OFFICE CELLULOS James mesne assignments, to Deny,Jersey City, N.

This invention relates to FABRICS, AND

Jersey No Drawing.

E ACETATE CREPE YARNS AND THEIR MANUFACTURE G. McNally, Rochester, N.Y., assignor, by

Eastman Kodak Com- J., a corporation of New Application February ,1,1936,

Serial No. 62,007

3 Claims.

crepe yarns and crepe fabrics and their production, and moreparticularly to crepe yarns and fabrics made of organic acid esters ofcellulose,

such as cellulose acetate,

5 cellulose propionate, cellulose butyrate, celluloseacetate-propionate, cellulose acetate-butyrate, celluloseacetate-stearate and the like.

It is customary in the art to employ for the manufacture of crepefabrics highly twisted yarns comprising cotton, natural silk, wool, orthe regenerated cellulose type of synthetic yarn,

hereinafter called rayon, and

the highly twisted yarn is referred-to as crepe yarn. Clothconstructions are very well known wherein crepe yarns are used either inwarp or filling or both,

but the crepe filling type which condition is largely of production ofthe present discussion is,

crepe therefore, more particuis the more popular, due to the lower costfilling fabric. The

larly directed to fabrics employing crepe filling yarns and it isunderstood late generally to warp crepes that the remarks rewithmodifications such as are obvious to a textile technician.

For certain novelty effects crepe yarns are used which comprise amixture of materials such as cotton-natural silk, natural silkrayon,nat-,

ural silk-cellulose acetate yarn, or rayon-cellulose acetate yarn. Thesemixtures are employed either as separate threads or two threads may betwisted together before pose usually of decreasing weaving for thepurthe cost of production of the fabric or of producing cross-dye orother novelty effects. It may be pointed out, however,

that in crepe constructions where cellulose acetate yarn is used in thefilling it is used'in conjunction with a crepe filling yarn of someother material and has no active crepe effect.

Cellulose acetate yarns use as warp yarns for crepe part in producingthe have found extensive fabrics because of the highly desirableproperties of fabrics made with these warps. The

filling yarn usually used in these popular constructions is rayon ornatural crepe yarn and the presence of two types of yarn, 1. leads todyeing difficulties owing to the fact that in general, unaflected by e.,cellulose acetate and rayon or silk,

in finishing the goods cellulose acetate yarn is,

dyes for rayon or natural silk and, similarly, dyes suitable forcoloring cellulose acetate yam are not'suitable for the other materials.It therefore becomes necessary to use separate dyes stituent yarns ofthese fabrics,

convenience and added the desirability of elimina for coloring theconwhich is an inexpense. Aside from ting this dyeing dimculty withacetate warp crepes, it has been found that crepe fabrics made entirelyof cellulose acetate yarns (both warp enhanced degree the durability,non-creasability, and excellent hand 5 and draping properties which areobtained by using cellulose acetate yarns in the warp alone. In orderthat the novel features of the instant invention may be clearlyapparent, a brief decrepe fabrics are at present 10 made, using rayon ornatural silk crepe filling, is

scription of the way and filling) show to an desirable properties ofhere given, the essential features of such present processes are thefollowing:

(1) Low turn rayon or natural silk yarn is soaked I in a solution ofsize, the excess solution removed and the yarn dried.

(2) The sized yarn is twisted, usually on an up draft twister, to from30 to 60 turns per inch,

depending upon the denier of the yarn and 20 the use to which it is tobe put. (3) After the operation (2) the yarn has a tendency to untwist.

To overcome this difficulty, the yarn is steamed while wound on spoolsto set the (4) The filling yarn the customary looms in crepe tions.

(5) The greige goods from jected to a boil off treatment in hot soapsolution to remove the twist of the yarn. 5 is wound on cops and used in2 fabric construc-- the loom are subsize from the yarn; the 30 fabricshrinks widthwise preferentially and develops a pebbled appearance ofcrepe fabrics. (6) The fabric is dyed characteristic on a winch machine,dried on a slack dryer, and framed out to the desired width on atentering frame. The finished crepe fabric has two outstandingcharacteristics: (1) A pebble or rough surface which varies in 40appearance depending on the type of crepe produced.

(2) Extensibility and elasticity which differentiate the cloth fromtightly woven construc- 45 tions such as taffetas or satins.

A popular construction for producing a rayon filled Canton crepe is asfollows:

Warp-112 ends per inch, denier dull cellulose acetate inch.

FiZling.-52 picks per inch 50 turns per yarn twisted to yarn, 40filaments, 4 turns per 50 of denier rayon inch, the filling constructionbeing two picks of right twist yarn alternating with two picks lefttwist yarn. 55

The greige goods are woven 50 inches wide in the loom.

When this fabric is woven, as indicated, into greige goods and boiledoff it shrinks in widthwise from 50 inches to 28-30 inches and developsa bumpy, finely pebbled surface. On framing in the tentering machine,the cloth is brought back to 39-40 inches in width and this representsthe finished dimension. The cloth shrinks longitudinally about -15 percent.

I am aware that the prior art reports many attempts to produce acellulose acetate crepe yarn. It was first proposed in the art toproduce cellulose acetate crepes by substantially imitating the methodof producing crepe from natural silk, involving sizing, twisting,setting, weaving and boiling off. Since that time it has been variouslyproposed to subject the yarn to shrinking treatments before weaving, totreat fabrics woven from cellulose acetate crepe yarns with bathscapable of swelling cellulose acetate, to partially saponify thecellulose acetate yarn before twisting, to incorporate water-solublematerials in the cellulose acetate crepe yarn, or to combine celluloseacetate yarns having different degrees of twist, using a relatively lowtwist in the doubling operation. It has further been proposed to producecloths of cellulose acetate having a puckered or crepe-like appearanceby subjecting cloths woven at least partly of cellulose acetate yarn totreatments calculated to cause differential shrinking of the variousyarns contained in the fabric. It may be said, however, that theseprocesses result in such very slight effects as to be scarcelyperceptible (widthwise contraction or shrinkage, due to creping,produced in the boiloif, not exceeding 10-15%) and are of no commercialimportance, as the resulting fabrics have none of the crepe propertiesexhibited by the rayon-filled Canton crepe.

Opposed to these teachings of the prior art, I have discovered that inthe production of true permit the creping action in the twisted yarn toassert itself.

possible to produce in accordance with my invention, a cellulose acetatecrepe, which has a widthwise contraction or shrinkage of approximately30-50%, which is necessary to produce a true crepe effect in the fabric.

It is, therefore, among the objects of my invention to produce, fromcellulose organic acid ester of employing a sizing or any process whichthermo-plastically molds the yarn. A further object of my invention isto produce true crepe fabrics.

acid ester yarns, such as cellulose acetate yarns, are satisfactory forcrepe yarns, particularly crepe filling yarns, if the twisting operationbe carried out while the yarn is in a softened, swollen condition, andthe twisted yarn then dried so as to maintain the twist. For the purposeof softening the yarn, I have successfully employed water alone,mixtures of water and other softening agents, aqueous emulsions ofvegetable, animal or mineral oils, solutions of soaps or other wettingor dispersing agents, and solutions of colloidal film-forming materials(which have a softening action but not essentially a sizing action) suchas gelatin, agar agar, water soluble cellulose esters and water solublepolyvinyl resins. Because of the simplicity of the operation, I preferto wet the yarn with the desired solution and to twist the yarn in onepassage through a down draft twister, but the invention can be carriedout on any other type of twisting equipment provided the yarn has beenwetted prior to the actual twisting step and has not dried out beforethe yarn is twisted. For example, the yarn may be wetted by running itthrough a trough, following which it is passed through a down drafttwister or wound on a spool which is put on the spindle of an up-drafttwister for twisting, or any other arrangement may be adopted whichprovides the essential feature of my method.

I have found it desirable in the operation of my invention to avoidexcessive stretching of the yarn prior to or during twisting, as theeffect is to change the molecular orientation of the fibers in such away that the desired property of the yarn of being able to assume aspiral configuration (the stable form of the twisted yarn) during anappropriate soaking or boil-off treatment is partly or entirely lost.For that reason, therefore, care must be taken to avoid undue tension onthe yarn while being wetted with the softening solution and theconditions on the twisting twisting, the size or denier of the yarn, andthe degree of twist being inserted. As a general rule, however, I employtensions not exceeding 0.15 gram per denier on the yarn; for example, a100 denier yarn should not be twisted by my method at a tension abovegrams, in order to avoid the impairment of the valuable crepingproperties of the yarn.

Following the preferred embodiment of my invention, it is found that thehighly twisted and dried cellulose acetate crepe yarn so produced issufficiently well set that it can be woven without any additionalconditioning treatment such as steaming.

Following the preparation of the crepe yarn, it is woven into fabric inthe usual manner for crepe fabrics. The fabric is then subjected to aboil-off bath which has a softening action upon the fabric, so as torelease the stored potential energy in the twisted thread and permit itto assert its creping effect. During the boil-off treatment, agitationof the fabric is highly desirable in order to assist the yarn to producethe crepe appearance in the cloth.

The following examples of the production of commercially valuablecellulose organic acid ester crepe fabrics, in accordance with myinvention,

aieaaco are intended to further the understanding of my invention, butwill be understood to be illustrative and not to limit its application,except as defined by the claims appended hereto.

Example I 100 denier cellulose acetate yarn was twisted to 55 turns perinch on a down-draft twister under a tension of grams. Just before theyarn passed through the feed roll of the twister, it was immersed forinches in an emulsion comprising Parts Water 100 Blown olive oil 5Glycerol 2 Soap 1 washing machine in the following solution:

Parts Carbitol acetate 10 Soap 0.2 Water 100 The fabric shrunk toapproximately 30 inches. The fabric was then rinsed, dyed in a dye box,tentered to a width of 40 inches and dried.

Example II 150 denier cellulose acetate yarn was wound onto an updrafttwister bobbin and then soaked thoroughly in the following solution:

The yarn was twisted without drying to 50 turns per inch on the up-drafttwister at a tension of 8 grams. Right and left twist yarn so preparedwas woven into a 50 inch fabric alternating six picks right and sixpicks left twist yarn at 48 picks per inch, the construction of the warpbeing 96 sley 150 denier cellulose acetate warp yarn having only a fewturns per inch. The crepe appearance was developed by working the fabricwith agitation on a dye reel containing the following solution at 40 0.:

Parts Ethyl aceto acetate T 7 Methyl alcohol 10 Sulfonated castor oil0.5 Soap 0.5 Water 100 The fabric shrunk to 2'1 inches. After thistreatment the cloth was rinsed, dried and tentered to a 40 inch width.

Example III 200 denier cellulose acetate yarn was twisted to 48 turnsper inch on a down-draft twister as described in Example 1, being wet inthetrough with:

Methyl Cellosolve ethylene glycol) The tension during twisting was 10grams.

The yam was woven into a 50 inch fabric alternating 4 picks left twistwith 4 right twist at 44 picks per inch into a cellulose acetate warp of120 denier 110 sley. The fabric was dyed and finished as in Example 1,using .the following boil-off bath at 45 0.:

Parts Paraldehyde 10 Ethyl alcohol 10 Water 100 The fabric shrunk to 25inches and was tentered to 39 inch width.

Example IV 75 denier cellulose acetate yarn was twisted to 55 turns perinch on a down-draft twister, as described in Example I, being wet inthe trough with Parts Water 100 Triethanolamine soap 2 Blown sesame oil10 the tension during twisting being '1 grams.

The yarn was woven into a 50 inch fabric, alternating 2 picks left twistwith 2 picks right twist, the warp being 135 sley 75 denier celluloseacetate yarn and the filling construction 58 picks per inch.

The fabric was dyed and finished as in Example I, using the followingboil-off bath at 40 0.:

Parts Water 100 Soap- 1 Diethyl carbonate 7 The fabric shrunk to 34inches and was tentered to 40 inches in width.

The result of the use of the softening bath, in the foregoing examples,prior to twisting of the yarn is somewhat difficult of explanation.Obviously, no softening bath should be employed which actually peptizesor in any way dissolves any portion of the yarn. The purpose of thesoftening bath is, contrary to the teachings of prior processes, toincrease the ductility of the yarn or to decrease the molecular ormicellar rigidity of the structural components of the yarn. This permitsthe molecules or micelles in the yarn, when twisted, to accommodate alarger reversible distortion than is the case when twisting dry yarn.The constituents of this softening bath are so proportioned and the timeof immersion of the yarn in the softening bath is so regulated that atsubstantially the end of'the twisting operation (as the yarn passesthrough the twister) the thread has substantially dried, or at least hasdried sufficiently to set the molecules or micelles in the yarn in theirnew positions or relation one to the other. Thus the twist in the yarnis set without destroying the reversible distortion therein.

As a general rule, the boil-off bath has a greater softening action uponthe fabric than does the softening bath employed prior to twisting. Infact, it will be noted that there is included in the softening baths ofthe four above examples, components which have a slight dissolvingaction upon the fabric, although due to the proportion used and the factthat large proportions of nonsolvents are employed, this solvent actionis considerably restrained. The reason for employing a boil-off bath ofthis character is that the warp yarn in the fabric resists thedevelopment a slight swelling action upon the yarn, the warp yarn, whichpredominates upon the surface of the fabric, is softened first, renderedmore pliable, and resistance to the creping action relieved; the fillingyarn then is acted upon by the boiloff bath, whereupon the set in theyarn is eliminated and the reversible torsion. in the yarn brought intoplay. Thus, with a soft warp the twisted filling creates the crepeappearance in the cloth. We do not mean to imply that the warp may notalso be twisted and thereby obtain additional novel effects; the sameexplanation would apply.

As a substitute for the above type of boil-off bath, it has been foundthat water alone may be used for the boil-off if the warp yarn hasincorporated therein certain softening agents such as diethylene glycol,Methyl Cellosolve (the mono methyl ether of ethylene glycol) butylcarbitol, butyl lactate, monoacetin, diacetin and the like. When thefabric contains such warp yarn, it is then subjected to the boil-offwith plain water or soap solutions, the warp is immediately softened dueto the interaction of the water with the softening agent, and thecreping action of the filling yarn is then able to assert itself.

While the foregoing examples and most of this specification haveemployed cellulose acetate yarn as the typical example, it is to beclearly understood that this invention is applicable to and includes theother cellulose organic acid esters, such for instance as cellulosepropionate, cellulose butyrate, cellulose acetate-propionate, celluloseacetate-butyrate, cellulose acetate-stearate and the like, and that theexamples and directions given herein are equally applicable to all ofthese esters, except that the softening bath and boil-off bath may haveto be altered somewhat to suitably increase or decrease the softeningand swelling action of the respective baths, in. order to effect thefull teachings of my invention.

I am aware that the wetting of yarn. to set the twist is old in the art.My process, however, is differentiated from this practice in that theyarn is wetted before and during twisting and not after any twist hasbeen inserted. I have found that yarns prepared by the two methods areclearly different in properties and that the necessary condition for theproduction of satisfactory cellulose acetate crepe filling yarn is thatthe yarn while being twisted be in a swollen, softened condition.

I am further aware that when cellulose acetate yarn is twisted for crepeyarn following accepted practice for viscose yarn, some slight crepeeffects can be obtained in cloth woven from these yarns. It is also wellknown that a very large number of patents have issued which claim toreveal processes which permit the production of commercially usefulcrepe fabrics, none of which have been found in actual practice to be atall satisfactory, as the products thereby obtained have little or nopermanent crepe effect. Attempts have evenv been made to simulate theappearance of true crepes by embossing crepelike patterns on celluloseacetate cloths and by weaving spiral figures in cellulose acetatecloths, which effects have been used in conjunction with the feeblecreping power of yarns prepared by known processes when boiled off byknown methods. However, the problem at hand is not the production ofsome slight waviness or cockled appearance in cellulose acetate cloths,which result could easily be accomplished by weaving design or byembossing flat cloth, but is the production of crepe cloth fromcellulose acetate yarns having the desirable appearance and feel ofnatural silk crepe fabrics, which products are commercially valuable.

Thus, it will be apparent that by my process, it is possible for thefirst time to produce crepe cloths which are true crepe fabrics and ofsuch a character that they are commercially valuable. By a true crepe ismeant a fabric having the appearance, feel and general properties ofcloths of similar construction which have long been known and made ofnatural silk or rayon yarns. By this I do not mean to imply thatcellulose acetate crepes cannot be made by my process in new and novelconstructions, but I do mean thereby to indicate that by my process thestandard crepe constructions can be successfully made and that thisinvention is not to be compared to socalled crepe fabrics involving thefeeble creping ability which has characterized cellulose acetate crepeyarns of earlier processes and prevented their commercial application.

One common feature of true" crepe fabrics is the large widthwiseshrinkage they undergo when the crepe appearance is developed in thefabric by an appropriate soaking or boil-off operation. For example, acrepe fabric woven 50 inches wide will shrink widthwise to approximately -34 inches when the crepe appearance is developed in accordancewith my invention, and the cloth also shrinks lengthwise 10-15 per cent.The shrinkage widthwise may in some rare constructions amount to aslittle as per cent of the original width but in general a widthwisecontraction of less than this amount results in an inferior fabric. Itis only possible to approach such shrinkage with cellulose acetatefilling yarn treated by the old silk or rayon twisting methods andboiling off the fabrics constructed of these yarns by the previouslyknown methods only if the warp construction is made so light that thefinished cloth is mechanically very weak and of no use for the customarypurposes of crepe fabrics.

The limiting factor to the improvement of crepe appearance by reductionof the number and size of the warp yarns, then, is the strength and appearance of the finished cloth; this limit is reached, from a practicalviewpoint, when the ratio of the total weight of filling yarn to thetotal weight of warp yarn is 1:1. Any increase in this ratio willproduce a cloth of very poor wearing properties, and although cloth witha somewhat cockled appearance could be made from cellulose acetate yarnsprior to this invention, they were of no commercial value.

What I claim is:

1. A process of producing a highly twisted cellulose organic acid estercrepe yarn capable, when woven into a crepe fabric construction, ofproducing a true crepe effect when the twist is released, whichcomprises treating cellulose organic acid ester yarn with an aqueoussoftening and swelling bath having substantially the same swellingeffect as water alone and maintained at ordinary room temperature andtwisting the yarn with a minimum of stretch while in a softened andswollen condition due to the presence in the yarn of an appreciableamount of water, and setting the twist without thermoplastically moldingthe yarn by drying simultaneously with or shortly after the twistingoperation.

2. The process of producing a highly twisted cellulose organic acidester crepe yarn capable, when woven into a crepe fabric construction,of

producing a true crepe effect when the twist is released, whichcomprises treating a substantially untwisted cellulose organic acidester yarn with a softening and swelling bath consisting essentially ofwater and maintained at a temperature of approximately 20 C., andtwisting the yarn with a minimum of stretch while in a softened andswollen condition due to the presence in the yarn of an appreciableamount of water, and setting the twist without thermopiastically moldingthe yarn by drying simultaneously with or shortly after the twistingoperation. a

3. The process of producing a highly twisted cellulose acetate crepeyarn capable, when woven into a crepe fabric construction, of producinga true crepe effect when the twist is released, which comprises treatinga substantially untwisted cellulose acetate yarn with a softening andswelling bath consisting essentially of water maintained atsubstantially room temperature, and twisting the yarn with a minimum ofstretch while in a softened and swollen condition due to the presence inthe yarn of an appreciable amount of water, and setting the twistwithout thermoplastically molding the yarn by drying simultaneously withor shortly after the twisting operation.

JAMES G. MONALLY.

